diff -up ./Server/src/test/java/org/openas2/message/AS2MessageMDNTest.java.tests ./Server/src/test/java/org/openas2/message/AS2MessageMDNTest.java

--- ./Server/src/test/java/org/openas2/message/AS2MessageMDNTest.java.tests	2017-07-25 23:14:10.868533190 -0400

+++ ./Server/src/test/java/org/openas2/message/AS2MessageMDNTest.java	2017-07-25 23:14:46.082526670 -0400

@@ -35,6 +35,6 @@ public class AS2MessageMDNTest {

     public void shouldGenerateMessageId() throws Exception

     {

         String messageId = new AS2MessageMDN(message, false).generateMessageID();

-        assertThat("Check " + messageId, messageId.matches("^OPENAS2-[0-9]{14}\\+[0-9]{4}-[0-9]{4}@senderId_receiverId"), is(true));

+        assertThat("Check " + messageId, messageId.matches("^OPENAS2-[0-9]{14}[+-][0-9]{4}-[0-9]{4}@senderId_receiverId"), is(true));

     }

-}

\ No newline at end of file

+}